Methods for polishing wafers used in electrical integrated circuits typically include a two step process of first, a primary polishing step, and second, a final polishing step. The primary polishing is a polishing process to remove surface defects as a result of, for example, deposition of metal onto the surface of a silicon substrate. The primary polishing process typically involves the use of a polishing composition in a chemical-mechanical polishing (CMP) process in which the polishing composition oxidizes a film surface of the substrate or wafer and removes the resultant oxide layer with the aid of solid abrasive grains.
However, the use of abrasives and/or oxidizing agents in the primary polishing solution is associated with various disadvantages such as creating scratches on the surface of the substrate, abrasives remaining attached to the substrate surface after polishing, and over polishing of the substrate. Typically, wafers have surface defects of approximately 10 to 50 μm after primary polishing, which are too great for satisfactory performance. Therefore, a second, final polishing is required.
The final polishing finishes a surface of a substrate by reducing surface roughness. However, the final polishing process typically uses a different polishing composition than that for the primary polishing process. Further, the final polishing composition typically does not result in high removal rates of materials on the substrate because the final polishing composition typically is more gentle than the primary polishing composition. As a result, the final polishing composition typically requires a longer polishing time and longer rinse time.
There exists a need for a polishing composition that results in low surface defects of the substrate undergoing polishing and achieves high removal rates.